Martial King's Retired Life - Chapter 75Book 15:

In the tenth year after the new era, the world finally came to an end. Zhang Mu truefully waited for his death, but unexpectedly found that he had returned to ten years ago. With his memory about the future, he swore that he would change the calamitous history, saving the earth from being destroyed! Walking dead, zergs, evolvers, and various mutated animals… nothing can stop him! The first step is to retrieve his identity as an era merchant , then find all the treasures he can remember to enhance himself!

- Description from Novelupdates

The world is full of mysteries. Strange, seemingly unexplainable events occur more often than we may realize. A young boy may catch an illness no doctor can explain. An office may catch fire for no apparent reason. And perhaps, someone may die a sudden and unexpected death – their bodies blighted beyond recognition.

In the new era when the earth began the test to become a Level 2 Civilization, everyone's Constellations played the most important role because only from them could people obtain skills.Having a contract with a stronger Constellation meant getting skills with a higher class.Money was the determinant of getting stronger Constellations as they offered skills to those who paid more.Oliver had no problem with that as he was raised by his aunt who was a super rich woman.That woman could contract one of the Strongest Constellations.However, she suddenly offended the Constellation she was about to contract, causing an inevitable conflict.As a result, that Constellation used his influence to make all Constellations not accept contracts from the two of them.Even with a lot of money, their status was destined to plummet in this new era if they did not have a Constellation.They had to be prepared for the attacks of their enemies.Unexpectedly for Oliver, when he felt hopeless, he accidentally joined a chat group that he initially thought contained strange people but turned out to be the most powerful figures in the universe.Even two of them casually gave him SSS+ Class Skills...

A man who was once called the world strongest agent ended up becoming a teacher after his retirement to train the new generation of agents. After many years of training his disciples, he is killed at the age of 60 by the ploy of a secret organization and was reincarnated in another world with all his past memories.Though he was surprised by the magic and the strange species of that world, he adapted very fast to his condition as a newborn and took advantage of it. He acquired special magic and gained a massive amount of strength thanks to his tight discipline in order to reach his goal: resume his career as a teacher which he left halfway through in his previous life.This is the story of a man who based on the memories and the experiences of his previous life, became a teacher who travels through the world with his new students.